The Rutgers team recently demonstrated “4D” printed hydrogel material that expands or contracts depending on the temperature. The study, published in Scientific Reports, uses a temperature-reactive hydrogel containing 73 percent water. The material creation process is fast, scalable, and capable of producing high-resolution 3D shapes. An example of the end process material in the form of a chess king piece maintains its shape but expands with temperatures above 90 degrees Fahrenheit and shrinks when the temperature drops below 90 degrees.

The engineers create the 4D objects with a 3D lithography printing technique using a hydrogel resin, a binder, a light-reactive bonding facilitator, and a dye to control light penetration. According to the researchers, they can print hydrogel shaped ranging from the width of a human hair to several millimeters in length. Potential applications for the 4D printed structures include structural support for organs, internal drug transport, soft robotics, and platforms for sensors and other biomedical devices.